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White Rider
01-19-2009, 04:29 PM
So due to my limited space in my single cab pickup i have 3 kenwood shallow subs. I am about to begin to build a box to go behind the seat and i have some questions. First is there a reason why i never see anyone with 3 subs? Can one amp power all 3 of them efficiantley? Also will porting make a big difference in the sound of these subs? I have an idea for external porting so i dont take away from the cubic feet space inside the box. And if i have a bit more than the recommended cubic feet of the box will that be better or are they tuned at that air space? And the length and space of the port is going to be a little different, does that make a big difference in the air exchange? There will probably be plenty more question but any information the you have would be great. Thanks

ThatChevyGuy
01-19-2009, 04:31 PM
shallow subs=sealed.

bonesninja
01-19-2009, 04:33 PM
So due to my limited space in my single cab pickup i have 3 kenwood shallow subs. I am about to begin to build a box to go behind the seat and i have some questions. First is there a reason why i never see anyone with 3 subs? Can one amp power all 3 of them efficiantley? Also will porting make a big difference in the sound of these subs? I have an idea for external porting so i dont take away from the cubic feet space inside the box. And if i have a bit more than the recommended cubic feet of the box will that be better or are they tuned at that air space? And the length and space of the port is going to be a little different, does that make a big difference in the air exchange? There will probably be plenty more question but any information the you have would be great. Thanks

most of the reason for have 2 or 4 versus three is because most people like whole numbers versus decimal points when figuring ohm load

White Rider
01-19-2009, 04:55 PM
shallow subs=sealed.

Really? I have heard that but i also have seen a shallow sub in a poted box and it did hit hard.


Also these subs are a 4ohm sub...and the amp is a RF 500 mono that puts out 500 at 1 ohm. Im very new to amps and dont know what that means. What does that need to be at to give the subss enough power? or do i need to match the ohms?

bonesninja
01-19-2009, 04:56 PM
good place to start reading

http://www.bcae1.com/

White Rider
01-19-2009, 05:10 PM
If thats true that you dont need to port the box does the box have to be divided into 3 sections? Or would it be better for the subs to be in 1 big enclosure?

z0n3d0u7
01-19-2009, 05:19 PM
Id divide it.

500 watts @ 1 ohm means your amp will put out that much when it see's that ohm load. Most amplifiers put out more power at lower ohm's. PG Xenons and JL slash series are regulated and put out the same power from 4 to 1 ohm.

Wiring 3 4 ohm DVC subs would give you a 2.66 ohm load, IIRC.
2 subs would give you the most power out of your amp. but power may not be the best bet vrs more surface area. Someone else MAY be able to answer that.

My friend was running 3 audiobahn 4ohm dvc subs off of a kicker 600.1 [600 watts at 2 ohm's.] and it hit pretty hard.

White Rider
01-19-2009, 05:30 PM
So runnin my amp at 1 ohm to all 3 of my subs would be the best; worst; horrible idea? Im just not sure what to do. The amp is 250watts at 4ohm, 400watts at 2ohm and 500watts at 1 ohm. Im unexperienced at elecronics right now and really have no idea what or even how to do this.

White Rider
01-19-2009, 08:08 PM
Any help or information would be great. About the box or the amp and subs. Thanks

qtipextra
01-19-2009, 08:20 PM
If they are single voice coil, and you wire them in parallel, you will end up with 1.33 Ohms.

Whereas this is close to 1 ohm, you should be able to get just about 500 watts RMS. (probably close to 450-475)

maseyferguson05
01-19-2009, 10:39 PM
Amps just don't have ohm switches. Its all about wiring. Heres how i think of it. The better and more efficient you wire them the less ohms and more power.

I'm sure someone can explain it way better than i can. Thats an easy way to understand it.

Trey803
01-19-2009, 10:44 PM
what are the factory recommendations?

White Rider
01-20-2009, 12:24 AM
what are the factory recommendations?


Heres a link to the amp.

http://www.sonicelectronix.com/item_9103_Rockford+Fosgate+Power+T500-1bd.html#

White Rider
01-20-2009, 01:33 AM
Amps just don't have ohm switches. Its all about wiring. Heres how i think of it. The better and more efficient you wire them the less ohms and more power.

I'm sure someone can explain it way better than i can. Thats an easy way to understand it.

So you mean by using....say 4 guage wire you could run more power than 16 guage wire? Or is there different ways to wire that make a big difference in the power?

qtipextra
01-20-2009, 10:35 AM
So you mean by using....say 4 guage wire you could run more power than 16 guage wire? Or is there different ways to wire that make a big difference in the power?

No, he means by wiring the subs together. This has (for general purposes) nothing to do with the gauge of wire that you use.

Refer to what I posted above. This is what you will want to do.

Alex JB
01-20-2009, 01:05 PM
As above, you need to understand how wiring a number of subs effects the load the amplifier sees.

Look at
http://www.crutchfield.com/App/Support/KnowledgeBase.aspx?ifs=subwoofer+wiring+diagrams

Plus, are the subs single or dual voice coil? (one or two sets of terminals on each one?)

amp roach
01-20-2009, 04:06 PM
Heres a link to the amp.

http://www.sonicelectronix.com/item_9103_Rockford+Fosgate+Power+T500-1bd.html#


dude you can get more power for cheaper

http://ikesound.com/alpine_mrp_m1000

White Rider
01-20-2009, 09:43 PM
dude you can get more power for cheaper

http://ikesound.com/alpine_mrp_m1000


Im not entirely sure if these subs really need that many watts. I think the RMS is 350 of my subs. I might eventually up the amperage, unless you know something i dont?

White Rider
01-20-2009, 09:55 PM
As above, you need to understand how wiring a number of subs effects the load the amplifier sees.

Look at
http://www.crutchfield.com/App/Support/KnowledgeBase.aspx?ifs=subwoofer+wiring+diagrams

Plus, are the subs single or dual voice coil? (one or two sets of terminals on each one?)

Yea i need to do more research and just look over my amp and figure it out too. The subs are single voice coil

White Rider
01-25-2009, 04:47 PM
I figured out all of my dimensions for my box size. The cubic feet I will have for each sub is .743 instead of the reccomended .8. The box is the full width of my cab and I have 2 dividers inside, to seperate the 3 subs.


So heres my question...would it be better to just run the three subs I have and them be under-boxed a bit, or just go to 2 subs and one divider in this enclosure? Also, If I ran two subs, that would get me back to 1 ohm instead of 1.33.

If I'm looking for the extra cubic feet with the three sub idea, and I move the subs closer to the back of my seat to make the box slightly bigger, will the performance of the sub go to hell being that close to the seat, or is this not a good trade off?

White Rider
01-26-2009, 03:34 PM
bump

Onebadsrt
01-27-2009, 08:28 AM
with that minimal of space i would prob run two subs in a ported but if you do the three i would def do sealed. As for the 2 bringing it back to 1 ohm. you need to check and see if you amp is 1ohm stable?

White Rider
01-27-2009, 01:49 PM
with that minimal of space i would prob run two subs in a ported but if you do the three i would def do sealed.
This is where I was unsure as to the best route. I obviously want it as loud as I can get it, but if two subs in a ported box with slightly more amperage (because of the one ohm instead of 1.33) would outperform three subs in a slightly to small sealed box, that is what I'll do. I've got the box all cut out right now and would like to get started puting it together, if I need to port this box I'll have to rethink this a bit. Also, how close can you run a sub to the back of your seat before you lose performance? I would think that if it were a hard object, the air would bounce, but since the seat is permeable, won't it just transfer through?


As for the 2 bringing it back to 1 ohm. you need to check and see if you amp is 1ohm stable?
I'm not sure what you mean by this. The amp is advertised 500x1@1ohm, is there something else I should be looking into? Thanks

Alex JB
01-27-2009, 04:36 PM
Take a look at the thread I posted about the response of my 2 sundown E8's

http://www.caraudio.com/forum/showthread.php?t=379353

take the same space and go from a tuned ported set up to a sealed enclosure and the curve is very different.

If you want loud and don't care about where in the freq range you could probably port your available space to 35-40Hz and make a lot of noise...
Bewarethough that whatever you play below the tuning frequency can damage the subs (over excursion) if you are over zealous with the volume.

I liked the loudness of my ported enclosure for about 10 mins then I missed the low frequency extension that sealed gave me (below the tune freq I had of 32-34Hz) so I've gone back to sealed for now.

If you have the right volume for 2 ported you should have more than enough for 3 sealed.
If you upped the power you could probably get as much out of the 3 sealed at the desired freq as the 2 ported... will take much more power to do it though.

White Rider
01-28-2009, 11:42 AM
If you want loud and don't care about where in the freq range you could probably port your available space to 35-40Hz and make a lot of noise...
Bewarethough that whatever you play below the tuning frequency can damage the subs (over excursion) if you are over zealous with the volume.

I liked the loudness of my ported enclosure for about 10 mins then I missed the low frequency extension that sealed gave me (below the tune freq I had of 32-34Hz) so I've gone back to sealed for now.

Yes I do want loud but, not at the cost of continuously killing speakers. This is my first system so I guess I also need to say "correct" is my target. I think I will be a little over sub'd until I get more speakers in the front, I just wanted to build the box one time. The more I read, it sounds like a sealed enclosure is what I need. I'm still unsure if it is possible to get the speakers to close to the back of my seat, anybody????:confused:


If you have the right volume for 2 ported you should have more than enough for 3 sealed.

This is another area I'm having problems with. The spec sheet that came with the subs said they go in a .8 box. Then they tell you the specs on the port, which is pictured as internal, so wouldn't that mean less area than a sealed box? So why is this backward from everybody's opinion on here? Could it be because these are shallows? Thanks

Alex JB
01-28-2009, 02:19 PM
Yes I do want loud but, not at the cost of continuously killing speakers. This is my first system so I guess I also need to say "correct" is my target. I think I will be a little over sub'd until I get more speakers in the front, I just wanted to build the box one time. The more I read, it sounds like a sealed enclosure is what I need. I'm still unsure if it is possible to get the speakers to close to the back of my seat, anybody????:confused:

As long as you have an inch or two from the speaker surround to the seat you should be fine, don't want them to rub and wear out the foam.


This is another area I'm having problems with. The spec sheet that came with the subs said they go in a .8 box. Then they tell you the specs on the port, which is pictured as internal, so wouldn't that mean less area than a sealed box? So why is this backward from everybody's opinion on here? Could it be because these are shallows? Thanks

Unless the subs are only recommended for either sealed or ported use, there will be two values for the volume... 0.8 cu ft for a 12 i'd guess is the sealed volume, look for a figure of 1.5 cu ft or more in the specs for ported.
Usually the ported spec is NET volume, this is after you deduct the speaker's volume and the port itself and bracing if you plan any.